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5 Written Questions

1. As K+ has reached conc grad of 2:1 the Cl- has also managed to reach 2:1 (in opposite direction). The conc grads cause potential. Calculating with Nernst = -17mV
2. The electrical potential that exactly balances a chemical concentration gradient for a specific ion
3. The difference between the chemical gradient and the electircal gradient.
4. The nernst equation defines equilibrium potential.
5. V=IR

5 Matching Questions

1. When should Cl- be used in GHK equation?
2. What happens with an excess of Sodium influx in respect to driving forces
3. What equation is Sodium conc used in?
4. Nernst Equation at Room Temp
5. Can Cl- contribute to Em?

1. a Higher Na movement would decrease Driving Force. This is because the membrane has moved slightly towards positive (Na is in higher concentration in the extracellular space). This causes the Driving Force for K to increase because there is now a larger differenc between membrane potential and equilibrium potential for K. This leads to more K moving out of cell and less Na into cell. Eventually the driving forces return to normal.
2. b Yes, cells that have Na+/K+/Cl- co transporter (ascending loop of henle). If Cl- is pumped into cell and the membrane is permeable there will be outward leak of Cl-. This is a depolarizing effect
3. c E = [-58/z] log [conc.in/conc.out]
4. d Goldman-Hodgkin-Katz
5. e Only when Cl- is not passively distributed.

5 Multiple Choice Questions

1. This is because the membrane will have a slight pNa which makes the cell more negative than EK+
   1. What is z in Nernst equation
   2. When DF is equal to 0
   3. Can Cl- contribute to Em?
   4. Why is Em close but not equal to EK+
2. 3Na+ out for every 2K+ in. This hyperpolarizes cell membrane (more negative)
   1. How many of each ion is used in Na+/K+ pump
   2. When should Cl- be used in GHK equation?
   3. Can Cl- contribute to Em?
   4. Nernst Equation at Room Temp
3. The presence of inpermeable anions in intracellular space
   1. When DF is equal to 0
   2. What complicates things with D.E?
   3. Can Cl- contribute to Em?
   4. What is z in Nernst equation
4. E = -58log { ([pK*Kin]/[pK*Kout]) + ([pNa*Nain]/[pNa*Naout]) + ([pCl*Clin]/[pCl*Clout]) }
   1. Rate of Flow
   2. Nernst Equation
   3. Current
   4. GHK equation
5. The difference between equilibrium potential and membrane potential
   1. Driving Force is also
   2. Rate of Flow
   3. Driving Force
   4. Membrane Potential

5 True/False Question

1. Does Cl- contribute to Em in most cells? → Yes, cells that have Na+/K+/Cl- co transporter (ascending loop of henle). If Cl- is pumped into cell and the membrane is permeable there will be outward leak of Cl-. This is a depolarizing effect
   

   True        False

2. What type of cells do not obey donnan effect? → Nerve cells do not obey donnan effect
   

   True        False

3. Step 2 of DE explanation → Cl- reaches conc equilibrium at 30mM each side. However, large K+ conc grad still exists so K+ still moves out. This means Cl- has to go with it.
   

   True        False

4. Rate of Flow → V=IR
   

   True        False

5. When DF is equal to 0 → E = ([RT] / [zF]) In (X1/X2)
   

   True        False